Field of Invention
The present invention relates to a method and a system for diagnosing failure of a gasoline direct injection (GDI) engine that diagnoses failure of a gasoline direct injection engine directly injecting fuel into a combustion chamber.
Description of Related Art
A gasoline direct injection (GDI) engine as a gasoline engine that directly injects fuel into a combustion chamber boosts fuel, which is supplied from a low-pressure fuel pump installed in a fuel tank, in a high-pressure fuel pump again and supplies the boosted fuel to an injector, in order to directly inject the fuel into the combustion chamber.
The gasoline direct injection engine is combined with a high-pressure system constituted by a high-pressure control valve, a high-pressure fuel pump, a fuel pressure sensor, and an injector; and a low-pressure system constituted by a low-pressure fuel pump, a fuel pump controller, and a fuel pressure sensor, thereby forming a GDI engine system.
In the GDI engine system, since fuel needs to be injected into the combustion chamber at high pressure, a fuel supply system further pressurizes fuel, which is primarily pressurized by the low-pressure system, in the high-pressure system. The fuel pressurized by the high-pressure system is directly injected into the combustion chamber through the injector.
In the GDI engine, problems such as an output shortage, excessive fuel consumption, and the like are caused when failure occurs in parts of a fuel system, and a result, the type of failure needs to be diagnosed.
One example of the existing GDI engine failure diagnosis (test) includes an evaporative leak test of judging whether which part of an evaporation system is in a failure state by measuring pressure in a fuel tank by controlling a purge valve with control logic of an engine control unit (ECU), when it is doubted that failure occurs in parts of the evaporation system of the GDI engine.
Further, part causing failure may be found by sensing a change in pressure in the tank by installing a fuel pressure sensor in the fuel tank.
However, in the case of the existing GDI engine, when failure occurs due to abnormal performance of the parts, not disconnection and a short-circuit, the engine control unit expresses only a failure code such as “low pressure to target pressure” or “high pressure to target pressure”, and as a result, a cause part (device) causes a phenomenon of not knowing what is the exact problem.
Therefore, in the related art, since the injector, the pump, the pressure sensor, and the like, which are fuel parts of the GDI engine, are arbitrarily replaced, the same problem may reoccur.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.